Objectives: Since epidemiologic trends of hepatitis A are changing worldwide, we studied its seroprevalence in Mumbai, which is thought to be a high-endemicity area. The immunogenicity and safety of a hepatitis A vaccine were also studied.
Methods: Six hundred and seventy subjects (456 men; age range 6 mo-60 y) answered a questionnaire on social and medical history. Qualitative analysis of total anti-HAV was performed in all subjects by ELISA. One hundred and seven of 147 anti-HAV negative subjects received hepatitis A vaccine at months 0, 1 and 6. Subjects were followed up (months 1, 2, 6, 7) to look for side-effects and seroconversion.
Results: The seroprevalence of HAV was 523/670 (78%); 38% of children < 5 years were anti-HAV negative. Seroprevalence rates of 80% were reached by 15 years. Prevalence was lower in the higher socio-economic group (151/234; 64.5%) compared with the lower socio-economic group (372/436; 85%) (p < 0.001). One month after doses 1, 2 and 3 of the hepatitis A vaccine, seropositivity was 92%, 99% and 100%, respectively. Minor self-limited side-effects occurred in 19.5% of subjects; there were no major side-effects.
Conclusions: The seroprevalence of anti-HAV is high in Mumbai. Seroprevalence is lower in the higher socio-economic groups. The hepatitis A vaccine is safe and immunogenic.
PIP: Prevention of hepatitis A virus (HAV) can be achieved through improved hygiene and living conditions, access to clean drinking water, and passive and active immunization. The present study assessed the age-related seroprevalence of HAV in Mumbai, India, in 1995-96 and the immunogenicity and safety of a newly developed inactivated HAV vaccine. 670 children and adults were recruited from 2 sites: a private hospital serving a predominantly middle- and upper-class population and a public hospital with low-income patients. Overall, 523 subjects (78%) were positive for anti-HAV. This rate was higher among low-income patients (85.3%) than those of higher socioeconomic status (64.5%). 38% of children under 5 years of age and 80% of those 11-15 years old were seropositive. 107 patients seronegative for anti-HAV were offered the vaccine. Anti-HAV antibody appeared 1 month after the first injection in 92.4% of vaccine recipients and 1 month after the second injection in 99%. Side effects were mild and self-limited. These findings confirm both the safety and the immunogenicity of the inactivated hepatitis A vaccine in high endemicity areas. However, universal immunization remains too costly in India. Further epidemiologic studies are needed to identify specific risk groups and regions that should be targeted for hepatitis A vaccine.